{"cve":{"cve_id":"CVE-2026-27586","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.00267,"epss_percentile":0.18139,"epss_as_of":"2026-06-23","description":"Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, two swallowed errors in `ClientAuthentication.provision()` cause mTLS client certificate authentication to silently fail open when a CA certificate file is missing, unreadable, or malformed. The server starts without error but accepts any client certificate signed by any system-trusted CA, completely bypassing the intended private CA trust boundary. Any deployment using `trusted_ca_cert_file` or `trusted_ca_certs_pem_files` for mTLS will silently degrade to accepting any system-trusted client certificate if the CA file becomes unavailable. This can happen due to a typo in the path, file rotation, corruption, or permission changes. The server gives no indication that mTLS is misconfigured. Version 2.11.1 fixes the vulnerability.","published_at":"2026-02-24T16:08:20.569000Z","last_modified_at":null,"cvss_v3_score":null,"cvss_v3_vector":null,"cvss_v3_severity":null,"cvss_v4_score":8.8,"cvss_v4_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","cvss_v4_severity":"HIGH","ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-755"],"nvd_references":["https://github.com/caddyserver/caddy/security/advisories/GHSA-hffm-g8v7-wrv7","https://gist.github.com/moscowchill/9566c79c76c0b64c57f8bd0716f97c48","https://github.com/caddyserver/caddy/releases/tag/v2.11.1"],"vuln_status":null,"trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:39.878444Z","updated_at":"2026-06-28T23:29:32.765824Z"},"effective_severity":"HIGH","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":null,"metrics":[]},"cvss_v4_decoded":{"version":"4.0","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"AT","name":"Attack Requirements","value":"N","value_label":"None"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"VC","name":"Confidentiality (Vulnerable System)","value":"H","value_label":"High"},{"metric":"VI","name":"Integrity (Vulnerable System)","value":"H","value_label":"High"},{"metric":"VA","name":"Availability (Vulnerable System)","value":"N","value_label":"None"},{"metric":"SC","name":"Confidentiality (Subsequent System)","value":"N","value_label":"None"},{"metric":"SI","name":"Integrity (Subsequent System)","value":"N","value_label":"None"},{"metric":"SA","name":"Availability (Subsequent System)","value":"N","value_label":"None"},{"metric":"E","name":"E","value":"P","value_label":"Physical"}]},"affected":[{"vendor_slug":"caddyserver","vendor_name":"caddyserver","product_slug":"caddy","product_name":"caddy","version_start":"< 2.11.1","version_start_inclusive":true,"version_end":"< 2.11.1","version_end_inclusive":true,"cpe23_uri":"cve5:caddyserver:caddy:< 2.11.1:< 2.11.1"}],"exploit_refs":[],"news":[],"references":[{"url":"https://github.com/caddyserver/caddy/security/advisories/GHSA-hffm-g8v7-wrv7","source_type":"VENDOR_ADVISORY","tags":["advisory"]},{"url":"https://gist.github.com/moscowchill/9566c79c76c0b64c57f8bd0716f97c48","source_type":"MISC","tags":[]},{"url":"https://github.com/caddyserver/caddy/releases/tag/v2.11.1","source_type":"PATCH","tags":["patch"]}],"timeline":[{"type":"published","at":"2026-02-24T16:08:20.569000Z","label":"CVE published","source":null},{"type":"cvss_changed","at":"2026-06-28T17:52:22.671512Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:52:22.671512Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:52:22.671512Z","label":"CVSS score revised","source":"cvelistv5"}]}